In my notes I see these variables and code being added in the Simple Timer lesson. So, to the best of my knowledge, nothing was skipped.
That said, it did seem like there were some lessons in this section where code was edited off-screen, but I usually mentioned that in my notes. I don’t think this was one of those instances.
This section was a bit tedious to follow.
But just stick with it. It’s still useful info, and the following section is a lot of fun.